Abstract: An integrated optical intensity modulator and a method for fabricating it. The integrated optical intensity modulator includes a substrate having spontaneous polarization, cut in an axial direction; an optical waveguide on the substrate; domain-inversion areas having domains reverse from the direction of spontaneous polarization, arranged in a staggered pattern around the optical waveguide; a first electrode on the optical waveguide on a surface of the substrate, and second and third electrodes on the substrate on opposite sides of and on the same surface as the first electrode. When a voltage is applied to the first electrode, a light wave is deflected and scattered in a domain-inversion area in accordance with a change of the refractive index of the domain-inversion area in the optical waveguide and the refractive index of the spontaneous polarization area.

Abstract: An integrated optics chip with improved performance when exposed to changing temperature is disclosed. The optic chip or integrated optics chip or MIOC has a top surface, a +Z face and -Z face. The integrated optics chip is formed from a crystal substrate having a high electro-optic coefficient such as Lithium Niobate. For the purpose of orienting the components to the optic chip to be described, the +Z crystal axis extends outward from the +Z face, the Z axis being the axis across which a pyroelectric effect is exhibited. The top surface is orthogonal to the Z axis. An input waveguide on the top surface receives an optical signal from an input port, passes the signal via a waveguide network, to an output waveguide coupling the waveguide network to an output port. A portion of the +Z and -Z faces are coated at least partially with a conductive coating.

Abstract: Method of fabricating a wavelength filter on a substrate in which a phase mask having corrugations is placed over a polymeric substrate composed of at least two comonomers having different indexes of refraction and passing light through the phase mask to form light into two beams corresponding to different diffraction orders to form refractive gratings capable of reflecting light of a selective wavelength. Optical signal devices employing gratings fabricated in this manner are also disclosed.

Abstract: A flat panel display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels.

Abstract: A switching element that selectively couples a first optical path to a second optical path through an index-matching fluid includes a tapering region along each of the optical paths to achieve high coupling efficiency at both ends of substrate waveguides that form portions of the two optical paths. The two substrate waveguides are separated by a gap that is filled with the index-matching fluid in order to optically couple the two waveguides. The ends of the waveguides located at the gap have relatively large cross sectional areas to promote high coupling efficiency across the gap. For example, the cross sectional dimensions may be approximately 16 .mu.m.times.8 .mu.m at the interior ends of the two substrate waveguides. On the other hand, the exterior ends have significantly smaller cross sectional areas in order to promote high coupling efficiency to optical fibers. For example, the cross sectional dimensions of an external end may be 8 .mu.m.times.8 .mu.m.

Abstract: An optical modulator including an optical waveguide structure and a selective modulation unit. The optical waveguide structure guides wavelength division multiplexed light including a plurality of optical carriers having different wavelengths. A modulation signal is supplied to the selective modulation unit. The selective modulation unit operates on the optical waveguide structure to selectively modulate a selected optical carrier selected from the plural optical carriers according to the modulation signal. With this configuration, the selective modulation unit operates on the single optical waveguide structure to perform selective modulation, so that optical modulation of an arbitrary optical carrier in the wavelength division multiplexed light can be easily performed.

Abstract: A new class of energy interaction devices, particularly optical energy transfer devices and energy guiding devices, use an energy field, particularly an electric field, applied to a poled structure to control energy propagation in a solid material. The poled structures, which may form gratings in thin film or bulk configurations, may be combined with waveguide structures to guide energy beams such as optical or acoustic beams. Electric fields applied to the poled structures, such as electrically-activated gratings, control routing of optical energy. Optical devices include but are not limited to, frequency-selective switchable- and adjustably-tunable reflectors, splitters, directional couplers, frequency-tunable switches and efficient beam combiners, as well as polarized beam combiners, am and fm modulators, mode selectors, energy transfer devices, optical data readers, panel display devices, and waveguide/reflector switching arrays.

Abstract: An optical beam splitting device which selectively disables a faulty output port to stop further emission of the optical beam therefrom. When an optical fiber cable is broken or a cable plug is disconnected, some part of the optical beam is reflected at the fiber end face that is left open. An optical sensing device, such as a photodiode, equipped in the beam splitting device receives this reflected light and transduces it into an electrical signal. A reflection detection controller examines this electrical signal and recognizes the presence of the back reflection if the electrical signal exceeds a predetermined reference level. The reflection detection controller then sends a beam control signal to an external modulator disposed at that faulty output port. With the beam control signal, the external modulator varies the intensity of the light beam so that only a limited power will be delivered to the faulty port where the back reflection is observed.

Abstract: The invention is related to technical physics, in particular to devices for investigating the internal structure of objects and can be used in medicine for diagnostics of human organs and systems, in particular for optical coherence tomography and in technical diagnostics, for example technological process control. The invention relates to the creation of an optical-fiber interferometer, which, being used in a device for optical coherence tomography, allows one to investigate media with short time of changing of optical characteristics or its position relative to the optical probe, for example biotissues in vivo. The invention also relates to the creation of a piezoelectric modulator, suitable for use in the interferometer and for providing the necessary scanning depth in the mentioned media.

Abstract: An apparatus, such as an optical modulator, which includes an optical waveguide and a polarizer housing device. The optical waveguide has an input end to receive light, and the polarizer housing device is connected to the input end of the optical waveguide. The polarizer housing device includes a polarizer which polarizes light, and a lens. A propagation space is in the polarizer housing device between the polarizer and the lens. The light polarized by the polarizer travels through the propagation space to the lens and is guided by the lens to the input end of the optical waveguide. The polarizer is bonded to the polarizer housing device with an adhesive so that no excess adhesive flows into the propagation space. Therefore, it is not necessary to use an optical adhesive to bond the polarizer to the polarizer housing device.

Abstract: A positioning apparatus positions free ends of resilient members. The apparatus couples a capacitance member to the free end and places the capacitance member within an electrode system. A voltage source applies an electric charge to the capacitance member and voltage signals applied to the electrode system generate electric fields which urge the free end to a position of equilibrium between an urging force of said electric field on said electric charge and an internal restoring force of said resilient member. This apparatus is adapted to also be a position sensing apparatus which includes a time-variable signal generator that is coupled to the capacitance member and a current sensor that senses current magnitudes in the electrodes of the electrode system. Each current magnitude is representative of the distance between that electrode and the capacitance member.

Abstract: A method for fabricating multi-layer polymer thin film of an electro-optical device which has a qualified multi-layer by using photobleaching characteristics of polymer. A proper time of photobleaching only changes the chemical, mechanical and electrical characteristics of the surface of the thin film without having any influence on characteristics of the device, so that when the multi-layer thin film are formed, such a cracking due to a solvent or melting, cracking due to the difference of mechanical tensile strength between each layer can be prevented, thereby obtaining a clean multi-layer thin film.

Abstract: A single fiber communication system which uses a short pulse light source in conjunction with a short pulse detector. The short pulse source transmits a short pulse carrier signal that is passed down an optical fiber to a reflective modulator. The reflective modulator imparts a modulation to the carrier and reflects it back up the fiber where it is detected by the short pulse light detector. Through the use of short pulses the invention is able to overcome the problem of fiber reflection. The reflected modulated pulse is easily separated from the undesired reflections from the fiber, thereby eliminating noise in the detected signal and increasing the effectiveness of the single fiber system.

Abstract: A cutoff mesa rib waveguide provides single-mode performance regardless of any deep etches that might be used for electrical isolation between integrated electrooptic devices. Utilizing a principle of a cutoff slab waveguide with an asymmetrical refractive index profile, single mode operation is achievable with a wide range of rib widths and does not require demanding etch depth tolerances. This new waveguide design eliminates reflection effects, or self-interference, commonly seen when conventional rib waveguides are combined with deep isolation etches and thereby reduces high order mode propagation and crosstalk compared to the conventional rib waveguides.

Abstract: An optical fiber sensor which is adapted for use in combination with a horseshoe-type iron core comprises a substrate having a groove pattern established by a pair of elongated spaced, parallel grooves, and a third groove which intersects the paired grooves at right angles. An optical fiber having a U-shaped portion is inserted into and fixed in the groove pattern, and an optical modulation unit, which is fixedly provided in a light path of the optical fiber, is placed in the third groove. The substrate is a composite which comprises a non-magnetic portion and soft magnetic portions fixed to either side of the non-magnetic portion. The paired elongated grooves are formed in the soft magnetic portions, while the optical modulation unit is fixed to the non-magnetic portion. A method for making such a composite substrate is also described.

Abstract: An integrated optical semiconductor device and an optical fiber gyroscope using the same. The semiconductor device comprises a super luminescence diode, at least one waveguide type photo-diode and at least one Y-branch integrated on a single semiconductor substrate. The waveguide structure of the super luminescence diode, photo-diode and Y-branch shares common optical guide layers formed by concurrent crystal growth. At least part of the optical guide layers are located on the side of the semiconductor substrate away from an active layer of the super luminescence diode and an optical absorption layer of the photo-diode.

Abstract: A photorefractive polymer waveguide is used to perform waveguide two beam coupling. Light incident on the waveguide interferes with scattered incident light or an input signal to create a modulated index pattern in the waveguide. The incident light is diffracted by the modulated index pattern to amplify signals in the waveguide in the direction of signal propagation.

Abstract: Optical systems use tuning of in-fiber gratings to provide an optical crossbar switch matrix of switch elements. The switch elements have a drop tap and an insert tap. A combination of the switch matrices provides a flexible way of connecting any of a plurality of transmitters with any of a plurality of receivers. A distribution arrangement has a distribution station with a plurality of serially arranged modulators, each modulating a different and corresponding optical carrier supplied by optical fiber thereto. The modulated carriers are supplied by a distribution fiber to a serially arranged plurality of passive taps, each of which drops an optical carrier corresponding to the tap and supplies it to a local transceiver. The distribution arrangement may include an arrangement where a local transceiver reflects back the modulated optical carrier and modulates it with a return signal.

Abstract: A compact display system including a viewing surface; a beam steering mechanism; a source of light remote from the viewing surface and the beam steering mechanism; and at least one waveguide connecting the source of light with the viewing surface for transmitting illumination from the source of light to the viewing surface. The beam steering mechanism is associated with the waveguide and the viewing surface for scanning illumination transmitted by the waveguide onto the viewing surface. There is a modulator for modulating the source of light; and a subsystem for synchronizing the modulator with the beam steering mechanism, but only the distal end of the waveguide and the beam steering mechanism are located near the viewing surface resulting in a more compact display which can be mounted on a pair of eyeglasses.

Abstract: Apparatus for mode coupling in a waveguide that includes an engagement substrate arranged for intimate contact with a waveguide, and at least two actuators coupled to the engagement substrate and operative to create an interference pattern in the engagement substrate for producing a periodic deformation of the waveguide.

Abstract: An optical deflection scanning device has a transducer, a waveguide medium for unidirectionally propagating an elastic wave based on the oscillation of the transducer. The light emitted from a light source is incident to the waveguide medium in a direction opposite the group velocity of the elastic wave in the waveguide medium. The incident light and elastic wave interact, and the incident light is deflected within the same plane as the waveguide medium in conjunction with elastic wave travel.

Abstract: A MQW semiconductor Mach Zehnder phase modulator is formed by two Y-junctions (12, 32), each having a single waveguide (14) optically coupled with two branch waveguides (18, 20). The branch waveguides of the two Y-juntions are optically coupled in Mach-Zehnder configuration that, under zero bias conditions, has one interferometric arm longer than the other to provide a .pi. phase shift. The additional length is preferably accommodated in the branches of the Y-junctions. The phase shift, in combination with voltage dependent absorption properties and non-linear phase variations of the MQW guided regions in the Mach-Zehnder modulator results in a negative chirp and high extinction ratio for an equal, push-pull device configuration.

Abstract: Optical fiber devices include optical fibers having grating portions with in-fiber gratings having optical characteristics which are changed by the use of strain inducing members. The strain inducing members are connected to optical fibers in such a way that the strain applied to an in-fiber grating in an optical fiber is greater than the strain in the strain inducing members. Basically, a given percentage change in a dimension of one of the strain inducing members causes a greater percentage change in a dimension of the grating portion. The strain inducing members may apply lengthwise or radial strain to the grating portion. Arrangements with mechanical coupling of two fibers using one or more strain inducing members are useful for producing equal strain in grating portions of two fibers for interferometer configurations or other applications.

Abstract: This invention is directed toward a fiber optic modulation and demodulation system, and more particularly directed toward a telemetry system for relaying signals from sensors in remote, harsh environments. Light is modulated using one or more optical reflective grating and piezoelectric crystal combinations, and demodulated using an interferometer system. The one or more modulators are driven by the responses of one or more sensors thereby modulating one or more carrier wavelengths of a carrier light source. The modulated light signal is transmitted from the sensor or sensors, over an optical fiber, to an interferometer which is used to demodulate the reflected signals and thereby determine the responses of one or more sensors. One embodiment of the invention set forth is that of a telemetry system linking sensors within a borehole to detection and processing equipment at the surface of the earth.

Abstract: A flat panel display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels.

Abstract: A tapped Bragg grating is used to demodulate optical signals reflected by ber optic Bragg gratings in a sensor in which the line spacings in the fiber optic Bragg gratings vary in response to a mechanical stress. A light detector, or light detector array is used to detect variation in the angular pattern of the light scattered by the tapped Bragg grating. Arrangements of mirrors, or alternatively arrangements of lenses, are used to concentrate the scattered light toward the light detectors and to enhance the angular changes in the scattered light.

Abstract: In a photostrictive device whose light-irradiated surface is irradiated with a beam of light with a specified wavelength to produce a photostrictive effect, the light-irradiated surface is formed with a surface roughness Ra related to the wavelength of light. This increases the light absorption of the photostrictive device, thereby improving the responsiveness.

Abstract: Computation-intensive applications such as sensor signal processing, sensor fusion, image processing, feature identification, pattern recognition, and early vision place stringent requirements on the computational capacity, size, weight, and power dissipation of modular computational systems intended for both embedded and high performance computer environments. Such ultra high speed, ultra high density computational modules will typically be configured with multiple processor, memory, dedicated sensor, and digital signal processing chips in close-packed multichip modules. The present invention relates to a novel architecture and associated apparatus for the development of highly multiplexed photonic interconnections between pairs of such electronic chips incorporated in vertical stacks within three-dimensional multichip module configurations.

Abstract: An electro-optic modulator/mode-converter with slow wave electrode is formed on a semiconductor substrate incorporating a waveguide interposed between a pair of spaced parallel conductor strips each provided with fins projected toward the other electrode and in position relative to the waveguide to electro-optically affect the waveguide when voltage is applied to the conductor strips. The modulator requires significantly less power and operates at higher frequency than Mach-Zehnder type slow wave modulators.

Abstract: A method is described for selectively modifying the refractive index of an optically transmissive body having an optical propagation axis. According to this method, polarized, actinic radiation is impinged on at least a portion of the body. In contrast to methods of the prior art, the actinic radiation is at least 60% polarized with a polarization direction parallel to a plane containing the propagation axis.

Abstract: A flat panel display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels.

Abstract: An optical transmission system transmits an optical signal. The optical transmission system may include an optical amplifier. The optical amplifier amplifies a received optical signal. A pumping light source outputs a pumping light beam and monitor information or supervisory information. This optical amplifier is adapted to amplify the received optical signal by propagating the received optical signal. An optical fiber which may be doped with a rare-earth element. An optical coupler couples the received optical signal and a first pumping light beam to the input of the optical fiber. Through propagation of the signal through the optical fiber, the received optical signal is amplified.

Abstract: A TE-TM mode converter of a polymer electro-optic polarization waveguide type uses the electro-optic birefringence and the electro-optic effect as a non-linear optical waveguide medium, in which an optical director formed during the poling of a polymer thin film is determined by the direction of the poling electrical field. The poling electrode design enables the optical director having the angle of 45.degree. to the electrical direction of the TE and TM modes to be formed in the polymer thin film. When the waveguide receives the incident light of the TE mode or TM mode, the TE (or TM) mode is switched into the TM (or TE) mode by an effective refraction factor between the optical director and the director perpendicular thereto. If a length of the poling electrode and the birefringence of the waveguide is adjusted, the changes of various electo-optic polarization states are possible. The poled thin film has an electro-optic effect.

Abstract: A programmable optical filter and an optical circuit arrangement using the filter has an optical demultiplexer for a spatial separation of the wavelengths from one another and a control arrangement composed of either an optical absorption modulator or an optical switch for controlled influencing of the light of the wavelength independent of other wavelengths. An optical amplifier may be arranged with each of the optical switches or absorption modulators.

Abstract: Integrated optical devices which utilize a magnetostrictively, electrostrictively or photostrictively induced stress to alter the optical properties of one or more waveguides in the device are disclosed. The integrated optical devices consist of at least one pair of optical waveguides preferably fabricated in a cladding material formed on a substrate. A stress applying material, which may be a magnetostrictive, electrostrictive or photostrictive material, is affixed to the upper surface of the cladding material near at least one of the optical waveguides. When the appropriate magnetic, electric or photonic field is applied to the stress applying material, a dimensional change tends to be induced in the stress applying material. The constrained state of the stress applying material, however, caused by its adhesion to the cladding material, causes regions of tensile and compressive stress, as well as any associated strains, to be created in the integrated optical device.

Abstract: An improved optical fiber modulator producing a focused acoustic wave propagating from an acoustic transducer surrounding an optical fiber having an in-fiber reflection grating changes the core refractive index in proportion to the induced strain at the core when the focused acoustic wave arrives at the optical fiber core, and focused acoustic waves can also modulate optical carrier phase in a length of optical fiber which may lie in an arm of an interferometer. In a preferred embodiment, the index change shifts the reflection spectrum of an in-fiber grating located in the portion of optical fiber core on which the focused acoustic wave is centered with the reflection spectrum shift producing a change in the grating reflectivity for a narrow bandwidth optical signal on a skirt of the grating spectrum.

Abstract: There is provided a method for modulating the polarization of light that allows detection of any modulated output regardless if the optical analyzers are rigidly held in place. According to a first aspect of the invention, a method for receiving light with a modulated polarization comprises steps of dividing the light being propagated through an optical fiber 1 with a polarization modulated in accordance with a modulation signal into three branched beams, causing one of the branched beams of light with a modulated polarization to pass through a .pi./2 phase corrector 2 and a first optical analyzer 3a and causing the remaining branched beams of light to respectively pass through second and third optical analyzers 3b and 3c without passing through any .pi./2 phase correctors before in order to receive light with a modualted intensity from the optical analyzers 3a, 3b and 3c.

Abstract: A wavelength conversion element includes a substrate made of LiTaO.sub.3 of non-linear medium, a three-dimensional waveguide formed in the substrate and a second harmonic generation portion for defining a change in refractive index in the waveguide with a period .LAMBDA. and generating a second harmonic of a fundamental wave introduced into the wave guide, where .LAMBDA.=2 m.pi./{.beta.(2.omega.)-2.beta.(.omega.)}, m is a natural number, .omega. is a frequency of fundamental harmonic, .beta.(.omega.) is a propagation constant of the fundamental wave, and .beta.(2.omega.) is a propagation constant of second harmonic.

Abstract: A method of magneto-optically modulating light comprises the steps of linearly polarizing the light on its transmission path, placing a magnetooptic effect element on the transmission path of the polarized light with the spontaneous magnetization direction of the element being parallel with the transmission path, the polarized light being modulated into a first light component when the plane of polarization of the polarized light is rotated to assume the first rotational position by the magnetooptic effect element in the absence of the applied magnetic field, applying the magnetic field to the magnetooptic effect element with the internal magnetization of the element being oriented in a direction perpendicular to the transmission path, the polarized light being modulated into a second light component when the plane of polarization of the polarized light is shifted to a second rotational position by the magnetooptic effect element in the presence of the applied magnetic field.

Abstract: A device for the optical processing of electrical signals. An optical source (L) emits a multiple-wavelength optical beam (B1). A modulator (MOD) modulates this beam. An optical fiber (F) receives the modulated beam and delays the components corresponding to the different wavelengths differently. A dispersive grating disperses wavelengths contained in the modulated beam in different directions. A spatial light modulator controls the level of optical intensity of different directions of the dispersed beam. An optical detection system receives the beam processed by the spatial light modulator. Such a device may find particular application to a transverse filter and microwave signal correlator.

Abstract: An optical modulator comprises an optical waveguide provided on an electro-optic substrate and formed of a first region for optical phase modulation and a second region for optical amplitude modulation cascaded with each other on the substrate, a signal electrode covering the optical waveguide for the first and second regions, and a ground electrode covering a surface of the substrate for the first and second regions, wherein the signal electrode includes an electrode strip extending on the surface of the substrate to continuously cover the optical waveguide from the first region to the second region, and wherein the ground electrode includes an electrode strip extending from the first region to the second region and covering the optical waveguide only in the first region.

Abstract: An optical modulation device includes a substrate. An optical waveguide is formed on the substrate. The optical waveguide exhibits an electro-optical effect. Parallel lines electromagnetically coupled with each other are formed on the substrate. The parallel lines extend at opposite sides of the optical waveguide respectively. The parallel lines are of a microstrip line structure. The parallel lines may alternatively be of a strip line structure or a coplanar line structure.

Abstract: A polarization-independent optical wavelength filter uses a polarization splitter to divide an optical input signal into first and second signals with mutually perpendicular planes of polarization. The first signal propagates via a first optical path to a first end of an optical device, such as a TE-TM mode converter or a polarization-dependent filter, that acts selectively on the desired wavelength, then returns via a second optical path from a second end of the optical device to the polarization splitter. The second signal propagates via the second optical path to the second end of the same optical device, and returns from the first end via the first optical path to the polarization splitter. The polarization splitter recombines the returning signals into an optical output signal consisting only of the desired wavelength.

Abstract: An interferometric modulator comprising a substrate of titanium-doped lithium niobate (Ti:LiNbO.sub.3) having top and bottom surfaces and a waveguide formed in the top surface is disclosed. A conductive layer is formed on the bottom surface of the substrate and electrically coupled to a top-surface ground plane or simply to ground potential. The bottom surface conductive layer functions to thermally stabilize the modulator during operation.

Abstract: An optical modulator in which waveguide regions are disposed at opposite ends of a modulation region to reduce the capacitance of the device and prevent pn junctions from exposure to air. On an n-side electrode there are laminated a substrate, an n-type clad layer and an optical modulation waveguide layer. A modulation region lies at the center of the optical modulation waveguide layer along the direction of travel of light, and two waveguide regions are disposed at opposite ends of the modulation region, respectively. On the optical modulation waveguide layer which constitutes the modulation region there are laminated a non-doped layer, a p-type clad layer and a p-side electrode, and a semi-insulating semiconductor is formed on the optical modulation waveguide layer which forms the two waveguide regions.

Abstract: An optical modulation method operable in an optical transmission path using an optical fiber, wherein an optical fiber bending region is formed by bending a portion of the optical fiber into a U shape having a predetermined bending width. A bending width set point is set in correspondence with a predetermined inclined portion of a characteristic curve representing a dependency ratio of insertion loss of light propagating in said optical fiber bending region relative to the bending width thereof, said predetermined inclined portion of said characteristic curve being located between a predetermined maximum and minimum portion thereof. Intensity modulation of light propagating in the optical fiber is performed using a signal to be transmitted by adjusting the bending width of the optical fiber bending region in correspondence with the signal to be transmitted with reference to the bending width set point as a center.

Abstract: An integrated optical receiver/transmitter (transceiver) 8 has continuous wave (cw) light 16 that enters a Mach-Zehnder optical modulator 10 controlled by a modulator control circuit 12 that provides modulated light 30 along a waveguide 32 to an optical coupler 34 which couples a predetermined portion of the light 30 to a waveguide 44 as light 42 which then exits the transceiver from a port 46. Receive light 90 is accepted at the port 46 and travels along the waveguide 44 to the coupler 34 which couples a predetermined amount of the light 90 to a waveguide 70 as light 92 which is detected by a waveguide-integrated photodetector 72. The photodetector 72 provides a current signal on a line 74 to a receiver circuit 76 which provides a voltage signal indicative of the light 92. Alternatively, the coupler may be passive, thereby not requiring the coupler control circuit, or no coupler at all may be employed and two fibers used for communications with the transceiver 8.

Abstract: Optical device including an optical waveguide composed of a LiTaO.sub.3 monocrystalline substrate and a LiNbO.sub.3 monocrystalline thin film waveguide formed on the surface of the substrate, with the lattice length of the LiNbO.sub.3 monocrystalline thin film waveguide and the LiTaO.sub.3 monocrystalline substrate being matched with each other, and an electrode provided on at least one of the branched sections of the waveguide extending along the optical axis thereof for changing a refractive index of the waveguide. The optical device having the optical waveguide has excellent electro-optic effects and a resistance to optical damage as well as an advanced modulation efficiency and a stable amplitude modulation.

Abstract: A wavelength conversion element includes a substrate made of LiTaO.sub.3 of non-linear medium, a three-dimensional waveguide formed in the substrate and a second harmonic generation portion for defining a change in refractive index in the waveguide with a period .LAMBDA. and generating a second harmonic of a fundamental wave introduced into the wave guide, where .LAMBDA.=2m.pi./{.beta.(2.omega.)-2.beta.(.omega.)}, m is a natural number, .omega. is a frequency of fundamental harmonic, .beta.(.omega.) is a propagation constant of the fundamental wave, and .beta.(2.omega.) is a propagation constant of second harmonic.

Abstract: A modulation assembly includes a fibre having a drawn tapered portion, and apparatus for applying a perturbation to the tapered portion to vary the percentage transmission through the fibre.